In:
Biogeosciences, Copernicus GmbH, Vol. 18, No. 24 ( 2021-12-14), p. 6377-6392
Abstract:
Abstract. Together with T–S properties, particle abundance in situ measurements are useful to
discriminate water masses and derive circulation patterns. In the upper
layers of the Ionian Sea, the fresher Atlantic Waters (AW) recently crossing
the Sicily Channel meet the resident and saltier AW, which circulated
cyclonically in the eastern basin and modified after evaporation and
eventually cooling. In May 2017, during the PEACETIME cruise, fluorescence
and particle abundance sampled at high resolution revealed unexpected
heterogeneity in the central Ionian Sea. Surface salinity measurements, together
with altimetry-derived and hull-mounted acoustic Doppler current profiler (ADCP) currents, describe a zonal
pathway of AW entering the Ionian Sea, consistent with the so-called
cyclonic mode in the North Ionian Gyre. The ION-Tr transect, located between
19–20∘ E at approximately 36∘ N, turned out to be at the
crossroads of three water masses, mostly coming from the west, north and
an isolated anticyclonic eddy northeast of ION-Tr. Using Lagrangian
numerical simulations, we suggest that the contrast in particle loads along
ION-Tr originates from particles transported from these three different
water masses. Waters from the west, identified as AW carried by a strong
southwestward jet, were moderate in particle load, probably originating from
the Sicily Channel. The water mass from the north, carrying abundant
particles, probably originated in the northern Ionian Sea, or further away
from the south Adriatic Sea. Waters from the eddy, depleted in particles and
chl a, may originate from south of the Peloponnese, where the Pelops eddy
forms. The central Ionian Sea hence appears as a mosaic area, where waters of
contrasted biological history meet. This contrast is particularly clear in
spring, when blooming and non-blooming areas co-occur. Interpreting the
complex dynamics of physical–biogeochemical coupling from discrete
measurements made at isolated stations at sea is a challenge. The
combination of multiparametric in situ measurements at high resolution with remote
sensing and Lagrangian modeling appears as one adequate way to address this
challenge.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-18-6377-2021
DOI:
10.5194/bg-18-6377-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2158181-2
